That is in series. With a PWM controller Input Current = Output Current With a MPPPT controller Output Current = Panel Wattage / Nominal Battery Voltage
It takes 18 volts per 12 volt of battery to charge them efficiently. That is why battery panels have 36 cells, each cell is .5 volts or a Vmp of 18 volts. Grid tied panels like your use more cells which is a good thing because higher voltage is more efficient and a lot cheaper. But you must use MPPT controller when using Grid Tied panels.
When you use a PWM controller like you have, you have to use expensive 36 cell battery panels. Example if you used your panels in parallel on a 12 volt battery system your charge power is reduced from 500 watts to 192 watts (16 amps x 12 volts) Just call it 200 watts or 100 watts from each 250 watt panel. Use a MPPT and you get roughly 475 watts when taking conversion losses into consideration and 475 watts @ 12 volts = 40 amps vs only 16 with PWM.
So now that you know go shopping for a 20 amp minimum MPPT controller. Be careful cheap ones are really PWM, check Voc input voltages, you want one with at 100 Voc input. A good one is going to cost you more than $200.
It takes 18 volts per 12 volt of battery to charge them efficiently. That is why battery panels have 36 cells, each cell is .5 volts or a Vmp of 18 volts. Grid tied panels like your use more cells which is a good thing because higher voltage is more efficient and a lot cheaper. But you must use MPPT controller when using Grid Tied panels.
When you use a PWM controller like you have, you have to use expensive 36 cell battery panels. Example if you used your panels in parallel on a 12 volt battery system your charge power is reduced from 500 watts to 192 watts (16 amps x 12 volts) Just call it 200 watts or 100 watts from each 250 watt panel. Use a MPPT and you get roughly 475 watts when taking conversion losses into consideration and 475 watts @ 12 volts = 40 amps vs only 16 with PWM.
So now that you know go shopping for a 20 amp minimum MPPT controller. Be careful cheap ones are really PWM, check Voc input voltages, you want one with at 100 Voc input. A good one is going to cost you more than $200.
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